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linux-next/fs/nilfs2/nilfs.h
Ryusuke Konishi 7ef3ff2fea nilfs2: fix deadlock of segment constructor over I_SYNC flag 
Nilfs2 eventually hangs in a stress test with fsstress program.  This
issue was caused by the following deadlock over I_SYNC flag between
nilfs_segctor_thread() and writeback_sb_inodes():

  nilfs_segctor_thread()
    nilfs_segctor_thread_construct()
      nilfs_segctor_unlock()
        nilfs_dispose_list()
          iput()
            iput_final()
              evict()
                inode_wait_for_writeback()  * wait for I_SYNC flag

  writeback_sb_inodes()
     * set I_SYNC flag on inode->i_state
    __writeback_single_inode()
      do_writepages()
        nilfs_writepages()
          nilfs_construct_dsync_segment()
            nilfs_segctor_sync()
               * wait for completion of segment constructor
    inode_sync_complete()
       * clear I_SYNC flag after __writeback_single_inode() completed

writeback_sb_inodes() calls do_writepages() for dirty inodes after
setting I_SYNC flag on inode->i_state.  do_writepages() in turn calls
nilfs_writepages(), which can run segment constructor and wait for its
completion.  On the other hand, segment constructor calls iput(), which
can call evict() and wait for the I_SYNC flag on
inode_wait_for_writeback().

Since segment constructor doesn't know when I_SYNC will be set, it
cannot know whether iput() will block or not unless inode->i_nlink has a
non-zero count.  We can prevent evict() from being called in iput() by
implementing sop->drop_inode(), but it's not preferable to leave inodes
with i_nlink == 0 for long periods because it even defers file
truncation and inode deallocation.  So, this instead resolves the
deadlock by calling iput() asynchronously with a workqueue for inodes
with i_nlink == 0.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-05 13:35:29 -08:00

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/*
* nilfs.h - NILFS local header file.
*
* Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Written by Koji Sato <koji@osrg.net>
* Ryusuke Konishi <ryusuke@osrg.net>
*/
#ifndef _NILFS_H
#define _NILFS_H
#include <linux/kernel.h>
#include <linux/buffer_head.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/nilfs2_fs.h>
#include "the_nilfs.h"
#include "bmap.h"
/**
* struct nilfs_inode_info - nilfs inode data in memory
* @i_flags: inode flags
* @i_state: dynamic state flags
* @i_bmap: pointer on i_bmap_data
* @i_bmap_data: raw block mapping
* @i_xattr: <TODO>
* @i_dir_start_lookup: page index of last successful search
* @i_cno: checkpoint number for GC inode
* @i_btnode_cache: cached pages of b-tree nodes
* @i_dirty: list for connecting dirty files
* @xattr_sem: semaphore for extended attributes processing
* @i_bh: buffer contains disk inode
* @i_root: root object of the current filesystem tree
* @vfs_inode: VFS inode object
*/
struct nilfs_inode_info {
__u32 i_flags;
unsigned long i_state; /* Dynamic state flags */
struct nilfs_bmap *i_bmap;
struct nilfs_bmap i_bmap_data;
__u64 i_xattr; /* sector_t ??? */
__u32 i_dir_start_lookup;
__u64 i_cno; /* check point number for GC inode */
struct address_space i_btnode_cache;
struct list_head i_dirty; /* List for connecting dirty files */
#ifdef CONFIG_NILFS_XATTR
/*
* Extended attributes can be read independently of the main file
* data. Taking i_sem even when reading would cause contention
* between readers of EAs and writers of regular file data, so
* instead we synchronize on xattr_sem when reading or changing
* EAs.
*/
struct rw_semaphore xattr_sem;
#endif
struct buffer_head *i_bh; /* i_bh contains a new or dirty
disk inode */
struct nilfs_root *i_root;
struct inode vfs_inode;
};
static inline struct nilfs_inode_info *NILFS_I(const struct inode *inode)
{
return container_of(inode, struct nilfs_inode_info, vfs_inode);
}
static inline struct nilfs_inode_info *
NILFS_BMAP_I(const struct nilfs_bmap *bmap)
{
return container_of(bmap, struct nilfs_inode_info, i_bmap_data);
}
static inline struct inode *NILFS_BTNC_I(struct address_space *btnc)
{
struct nilfs_inode_info *ii =
container_of(btnc, struct nilfs_inode_info, i_btnode_cache);
return &ii->vfs_inode;
}
/*
* Dynamic state flags of NILFS on-memory inode (i_state)
*/
enum {
NILFS_I_NEW = 0, /* Inode is newly created */
NILFS_I_DIRTY, /* The file is dirty */
NILFS_I_QUEUED, /* inode is in dirty_files list */
NILFS_I_BUSY, /* inode is grabbed by a segment
constructor */
NILFS_I_COLLECTED, /* All dirty blocks are collected */
NILFS_I_UPDATED, /* The file has been written back */
NILFS_I_INODE_SYNC, /* dsync is not allowed for inode */
NILFS_I_BMAP, /* has bmap and btnode_cache */
NILFS_I_GCINODE, /* inode for GC, on memory only */
};
/*
* commit flags for nilfs_commit_super and nilfs_sync_super
*/
enum {
NILFS_SB_COMMIT = 0, /* Commit a super block alternately */
NILFS_SB_COMMIT_ALL /* Commit both super blocks */
};
/*
* Macros to check inode numbers
*/
#define NILFS_MDT_INO_BITS \
((unsigned int)(1 << NILFS_DAT_INO | 1 << NILFS_CPFILE_INO | \
1 << NILFS_SUFILE_INO | 1 << NILFS_IFILE_INO | \
1 << NILFS_ATIME_INO | 1 << NILFS_SKETCH_INO))
#define NILFS_SYS_INO_BITS \
((unsigned int)(1 << NILFS_ROOT_INO) | NILFS_MDT_INO_BITS)
#define NILFS_FIRST_INO(sb) (((struct the_nilfs *)sb->s_fs_info)->ns_first_ino)
#define NILFS_MDT_INODE(sb, ino) \
((ino) < NILFS_FIRST_INO(sb) && (NILFS_MDT_INO_BITS & (1 << (ino))))
#define NILFS_VALID_INODE(sb, ino) \
((ino) >= NILFS_FIRST_INO(sb) || (NILFS_SYS_INO_BITS & (1 << (ino))))
/**
* struct nilfs_transaction_info: context information for synchronization
* @ti_magic: Magic number
* @ti_save: Backup of journal_info field of task_struct
* @ti_flags: Flags
* @ti_count: Nest level
*/
struct nilfs_transaction_info {
u32 ti_magic;
void *ti_save;
/* This should never used. If this happens,
one of other filesystems has a bug. */
unsigned short ti_flags;
unsigned short ti_count;
};
/* ti_magic */
#define NILFS_TI_MAGIC 0xd9e392fb
/* ti_flags */
#define NILFS_TI_DYNAMIC_ALLOC 0x0001 /* Allocated from slab */
#define NILFS_TI_SYNC 0x0002 /* Force to construct segment at the
end of transaction. */
#define NILFS_TI_GC 0x0004 /* GC context */
#define NILFS_TI_COMMIT 0x0008 /* Change happened or not */
#define NILFS_TI_WRITER 0x0010 /* Constructor context */
int nilfs_transaction_begin(struct super_block *,
struct nilfs_transaction_info *, int);
int nilfs_transaction_commit(struct super_block *);
void nilfs_transaction_abort(struct super_block *);
static inline void nilfs_set_transaction_flag(unsigned int flag)
{
struct nilfs_transaction_info *ti = current->journal_info;
ti->ti_flags |= flag;
}
static inline int nilfs_test_transaction_flag(unsigned int flag)
{
struct nilfs_transaction_info *ti = current->journal_info;
if (ti == NULL || ti->ti_magic != NILFS_TI_MAGIC)
return 0;
return !!(ti->ti_flags & flag);
}
static inline int nilfs_doing_gc(void)
{
return nilfs_test_transaction_flag(NILFS_TI_GC);
}
static inline int nilfs_doing_construction(void)
{
return nilfs_test_transaction_flag(NILFS_TI_WRITER);
}
/*
* function prototype
*/
#ifdef CONFIG_NILFS_POSIX_ACL
#error "NILFS: not yet supported POSIX ACL"
extern int nilfs_acl_chmod(struct inode *);
extern int nilfs_init_acl(struct inode *, struct inode *);
#else
static inline int nilfs_acl_chmod(struct inode *inode)
{
return 0;
}
static inline int nilfs_init_acl(struct inode *inode, struct inode *dir)
{
inode->i_mode &= ~current_umask();
return 0;
}
#endif
#define NILFS_ATIME_DISABLE
/* Flags that should be inherited by new inodes from their parent. */
#define NILFS_FL_INHERITED \
(FS_SECRM_FL | FS_UNRM_FL | FS_COMPR_FL | FS_SYNC_FL | \
FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL | FS_NOATIME_FL |\
FS_COMPRBLK_FL | FS_NOCOMP_FL | FS_NOTAIL_FL | FS_DIRSYNC_FL)
/* Mask out flags that are inappropriate for the given type of inode. */
static inline __u32 nilfs_mask_flags(umode_t mode, __u32 flags)
{
if (S_ISDIR(mode))
return flags;
else if (S_ISREG(mode))
return flags & ~(FS_DIRSYNC_FL | FS_TOPDIR_FL);
else
return flags & (FS_NODUMP_FL | FS_NOATIME_FL);
}
/* dir.c */
extern int nilfs_add_link(struct dentry *, struct inode *);
extern ino_t nilfs_inode_by_name(struct inode *, const struct qstr *);
extern int nilfs_make_empty(struct inode *, struct inode *);
extern struct nilfs_dir_entry *
nilfs_find_entry(struct inode *, const struct qstr *, struct page **);
extern int nilfs_delete_entry(struct nilfs_dir_entry *, struct page *);
extern int nilfs_empty_dir(struct inode *);
extern struct nilfs_dir_entry *nilfs_dotdot(struct inode *, struct page **);
extern void nilfs_set_link(struct inode *, struct nilfs_dir_entry *,
struct page *, struct inode *);
/* file.c */
extern int nilfs_sync_file(struct file *, loff_t, loff_t, int);
/* ioctl.c */
long nilfs_ioctl(struct file *, unsigned int, unsigned long);
long nilfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
int nilfs_ioctl_prepare_clean_segments(struct the_nilfs *, struct nilfs_argv *,
void **);
/* inode.c */
void nilfs_inode_add_blocks(struct inode *inode, int n);
void nilfs_inode_sub_blocks(struct inode *inode, int n);
extern struct inode *nilfs_new_inode(struct inode *, umode_t);
extern void nilfs_free_inode(struct inode *);
extern int nilfs_get_block(struct inode *, sector_t, struct buffer_head *, int);
extern void nilfs_set_inode_flags(struct inode *);
extern int nilfs_read_inode_common(struct inode *, struct nilfs_inode *);
extern void nilfs_write_inode_common(struct inode *, struct nilfs_inode *, int);
struct inode *nilfs_ilookup(struct super_block *sb, struct nilfs_root *root,
unsigned long ino);
struct inode *nilfs_iget_locked(struct super_block *sb, struct nilfs_root *root,
unsigned long ino);
struct inode *nilfs_iget(struct super_block *sb, struct nilfs_root *root,
unsigned long ino);
extern struct inode *nilfs_iget_for_gc(struct super_block *sb,
unsigned long ino, __u64 cno);
extern void nilfs_update_inode(struct inode *, struct buffer_head *, int);
extern void nilfs_truncate(struct inode *);
extern void nilfs_evict_inode(struct inode *);
extern int nilfs_setattr(struct dentry *, struct iattr *);
extern void nilfs_write_failed(struct address_space *mapping, loff_t to);
int nilfs_permission(struct inode *inode, int mask);
int nilfs_load_inode_block(struct inode *inode, struct buffer_head **pbh);
extern int nilfs_inode_dirty(struct inode *);
int nilfs_set_file_dirty(struct inode *inode, unsigned nr_dirty);
extern int __nilfs_mark_inode_dirty(struct inode *, int);
extern void nilfs_dirty_inode(struct inode *, int flags);
int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
__u64 start, __u64 len);
static inline int nilfs_mark_inode_dirty(struct inode *inode)
{
return __nilfs_mark_inode_dirty(inode, I_DIRTY);
}
static inline int nilfs_mark_inode_dirty_sync(struct inode *inode)
{
return __nilfs_mark_inode_dirty(inode, I_DIRTY_SYNC);
}
/* super.c */
extern struct inode *nilfs_alloc_inode(struct super_block *);
extern void nilfs_destroy_inode(struct inode *);
extern __printf(3, 4)
void nilfs_error(struct super_block *, const char *, const char *, ...);
extern __printf(3, 4)
void nilfs_warning(struct super_block *, const char *, const char *, ...);
extern struct nilfs_super_block *
nilfs_read_super_block(struct super_block *, u64, int, struct buffer_head **);
extern int nilfs_store_magic_and_option(struct super_block *,
struct nilfs_super_block *, char *);
extern int nilfs_check_feature_compatibility(struct super_block *,
struct nilfs_super_block *);
extern void nilfs_set_log_cursor(struct nilfs_super_block *,
struct the_nilfs *);
struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
int flip);
int nilfs_commit_super(struct super_block *sb, int flag);
int nilfs_cleanup_super(struct super_block *sb);
int nilfs_resize_fs(struct super_block *sb, __u64 newsize);
int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
struct nilfs_root **root);
int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno);
/* gcinode.c */
int nilfs_gccache_submit_read_data(struct inode *, sector_t, sector_t, __u64,
struct buffer_head **);
int nilfs_gccache_submit_read_node(struct inode *, sector_t, __u64,
struct buffer_head **);
int nilfs_gccache_wait_and_mark_dirty(struct buffer_head *);
int nilfs_init_gcinode(struct inode *inode);
void nilfs_remove_all_gcinodes(struct the_nilfs *nilfs);
/* sysfs.c */
int __init nilfs_sysfs_init(void);
void nilfs_sysfs_exit(void);
int nilfs_sysfs_create_device_group(struct super_block *);
void nilfs_sysfs_delete_device_group(struct the_nilfs *);
int nilfs_sysfs_create_snapshot_group(struct nilfs_root *);
void nilfs_sysfs_delete_snapshot_group(struct nilfs_root *);
/*
* Inodes and files operations
*/
extern const struct file_operations nilfs_dir_operations;
extern const struct inode_operations nilfs_file_inode_operations;
extern const struct file_operations nilfs_file_operations;
extern const struct address_space_operations nilfs_aops;
extern const struct inode_operations nilfs_dir_inode_operations;
extern const struct inode_operations nilfs_special_inode_operations;
extern const struct inode_operations nilfs_symlink_inode_operations;
/*
* filesystem type
*/
extern struct file_system_type nilfs_fs_type;
#endif /* _NILFS_H */
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